A lot of imaging systems for imaging a region of interest are known, for example, computed tomography systems, magnetic resonance imaging systems, ultrasound imaging systems or nuclear imaging systems. Images generated by these imaging systems generally comprise artefacts, which can be caused by different effects, for example, by movements within a region of interest, which has to be imaged, or by high density elements like metallic elements, which influence radiation traversing the region of interest.
In computed tomography systems, which use an X-ray source emitting X-rays and a detection unit for detecting the X-rays after having traversed the region of interest, metallic elements, for example, metal implants like hip replacements or dental fillings, cause severe artefacts in the reconstructed images. In order to reduce these artefacts, it is known to identify a shadow of the metallic elements in a sinogram, which is constituted of the detection values detected by the detection unit, for example, by thresholding, and to replace the detection values in the identified shadow by calculated values, which are determined by interpolation. A combination of detection values outside of the shadow and of the calculated values in the identified shadow is used for reconstructing an image of the region of interest. But even by using this artefact correction method, strong arte-facts are still present in the reconstructed image, resulting in a decreased image quality.